Gas turbine with bearing cooling means

ABSTRACT

A regenerative gas turbine engine in which each of the turbine shaft bearings is supported in a housing which forms part of a lubricating system and which has oilways leading to and from the corresponding bearing. Surmounting the bearing housing is an oil reservoir which, during running of the engine, becomes filled with oil bled from one of the oilways of the bearing housing. The reservoir has at its top an overflow hole through which surplus oil is returned to a sump and, when the engine is shut down, the oil stored in the reservoir is exploited to cool the shaft bearings.

United States Patent 15] 3,692,146 Butler 5] Sept. 19, 1972 [54] GASTURBINE WITH BEARING FOREIGN PATENTS OR APPLCATIONS COOLING MEANS I721Inventor @IYPQE'E? But flsql hu r En land [73] Assignee: Leyland GasTurbines Solihull, England Limited,

Filed: Feb. 8, 1971 Appl. No.: 113,314

[56] References Cited UNITED STATES PATENTS 9/1958 Eberle et a1..184/6.1 X 6/1971 Edge ..l84/6.11

1,047,820 12/1958 Germany ..184/6.12 658,044 10/1951 Great Britain 184/61 1 740,513 11/1955 Great Britain 184/63 Primary Examiner-Manuel A.Antonakas Attorney-Holcombe, Wetherill & Brisebois [57] ABSTRACT Aregenerative gas turbine engine in which each of the turbine shaftbearings is supported in a housing which forms part of a lubricatingsystem and which has oilways leading to and from the correspondingbearing. Surmounting the bearing housing is an oil reservoir which,during running of the engine, becomes filled with oil bled from one ofthe oilways of the bearing housing. The reservoir has at its top anoverflow hole through which surplus oil is returned to a sump and, whenthe engine is shut down, the oil stored in the reservoir is exploited tocool the shaft bearings.

, /5 8A 49 3 5 \l\)\ V4 1' GAS TURBINE WITH BEARING C(JOLING MEANS Thisinvention relates to gas turbine engines of the regenerative kind,namely, having a heat-exchanger and a thermally-insulated main casing.

In regenerative gas turbine engines, heat supplied to the nozzles andturbine rotors during running is not readily conducted to atmosphere onshut down, and can cause overheating of the bearings under theseconditions, when the supply of cooling oil (from the'engines lubricatingsystem) to the bearings normally ceases.

The object of the invention is to make provision for ensuring that areserve of cooling oil is available to extract heat from the bearingsfor a sufficient period after the engine is shut down, in order toprevent overheating of the bearings by the heat which soaks back fromthe hotter parts of the engine. To this end, according to the inventiona regenerative gas turbine engine has each of its turbine shaft bearingssupported in a housing which forms part of a lubricating system andwhichhas oilways leading to and from the corresponding bearing;surmounting the bearing housing is an oil reservoir which, duringrunning of the engine, becomes filled with oil bled from one of theoilways ofthe bearing housing; the reservoir has at its top an overflowhole through which surplus oil is returned to a sump; and, when theengine is shut down, the oil stored in the reservoir is exploited tocool the shaft bearings.

Referring to the accompanying drawings:

FIG. 1 is a sectional elevation of the turbine shaft bearings of aregenerative gas turbine engine which'incorporates the invention; and

FIG. 2 is a fragmentary view, to a larger scale, illustratin g analternative embodiment of the invention.

In the embodiment shown in FIG. 1, a turbine rotor 1 of a regenerativegas turbine engine has its shaft 2 mounted in bearings 3 and 4 which aresupported in a housing 5. When the engine is running, the bearings 3 and4 are supplied with oil under pressure from the usual engine-drivenlubricating pump (not shown). The oil from the pump flows throughoilways 6 and 7, and reaches the bearings 3 and 4 through drillings 8and 9 in the upper part of the bearing housing 5. Further drillings land 11 in the lower part of the bearing housing allow the oil to drainthrough an oilway 12 to an auxiliary gearbox 13 suspended beneath oneend of the bearing housing 5, and thence through an outlet 14 to theengine oil sump.

Surrounding the bearing housing 5 and the auxiliary gearbox 13 is astepped cylindrical casting 15 which, at the smaller end, houses an oilseal 16 between the bearing 3 (which is a roller bearing) and theturbine rotor 1. The turbine shaft 2 has another oil seal 17 locatedbeyond the bearing 4. A closing member 18 at the larger end of thestepped casting 15 forms a back-plate for the compressor and diffuser(which are not shown). An annular space 19 between the inner diameter ofthe smaller end of the stepped casting l5 and the outer diameter of thebearing housing 5 is fed with oil through an extension 8A of the bearingoil supply reservoir 21 which, at its base, is fed by a drilling 22 fromthe annular space 19. There is an overflow hole 23 at the top of thereservoir 21 through which surplus oil can retiilrn to the sump.

When t e engine 18 running, there is a continuous supply of oil to thebearings 3 and 4, and, in addition, first the annular space 19 is filledwith oil and then the reservoir 21. When the engine is stopped, oil fromthe reservoir 21 flows by gravity throughthe bearing housing 5 and thebearings Band 4, and drains back to the sump. In this way the reserveoil supply continues to cool the bearings 3 and 4 after the engine isshut down.

In the alternative embodiment of the invention (see FIG. 2) aspring-loaded non-return valve 24 is fitted in the oil supply drilling8A to the annular space 19, and

the drilling 22 (FIG. 1) between the annular space and base of thereservoir 21 is enlarged. The oil does not then drain back through thebearings on shut down, but remains in the reservoir 21. Since this oilis heated at the bottom by the bearing housing 5 and is relatively coolat the top, which is adjacent to the diffuser, the oil circulates byconvection on shut down and, in this way, cools the shaft bearings 3 and4.

I claim:

1. A regenerative gas turbine engine provided with a reservoir for oilfor cooling the bearing parts of said turbine engine upon shutdown ofthe said engine, said turbine having turbine shaft bearings supported ina housing which forms a part of a lubricating system, oilways leading toand from said bearings, said oil reservoir surmounting said housing,surrounded by a stepped cylindrical casting, and the upper partof thelarger end of this stepped casting is separated from the remainder ofthe casting by a substantially horizontal cordal wall to form the oilreservoir, said reservoir becoming filled with oil from one of saidoilways during operation of the engines, an overflow for said oil insaid reservoir, said oil in said reservoir draining onto the said shaftbearings for cooling the same upon a shutdown of the engine.

2. A regenerative gas turbine engine according to claim 1, in which anannular space between the inner diameter of the smaller end of thestepped casting and the outer diameter of the bearing housing is fedwith oil through an extension of an oilway of the bearing housing, andthe reservoir receives oil from the annular space.

3. A regenerative gas turbine engine according to claim 2, in which theoilwayextension is fitted with a spring-loaded non-return valve whichcauses oil to be retained in the reservoir on shut down.

4. A regenerative gas turbine engine according to claim 1 wherein anauxiliary gearbox suspended beneath one end of the bearing housingreceives oil through drillings and an oilway in the lower part of thebearing housing. 7

UNITED STATES PA'IENT OFFICE CERTIFICATE OF CORRECTION Patent No. 9Dated September 19, 1972 LAWRENCE BUTLER Inventor(s) It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

[30] Foreign Application Priority Data February 19, 1970 Great Britain7701/70 Signed and sealed this 13th day of February 1973..

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORMPO-1050(10-69l USCOMM-DC 60376-P69 v.5, GOVERNMENT PRINTING OFFICE: I56903u-334

1. A regenerative gas turbine engine provided with a reservoir for oilfor cooling the bearing parts of said turbine engine upon shutdown ofthe said engine, said turbine having turbine shaft bearings supported ina housing which forms a part of a lubricating system, oilways leading toand from said bearings, said oil reservoir surmounting said housing,surrounded by a stepped cylindrical casting, and the upper part of thelarger end of this stepped casting is separated from the remainder ofthe casting by a substantially horizontal cordal wall to form the oilreservoir, said reservoir becoming filled with oil from one of saidoilways during operation of the engines, an overflow for said oil insaid reservoir, said oil in said reservoir draining onto the said shaftbearings for cooling the same upon a shutdown of the engine.
 2. Aregenerative gas turbine engine according to claim 1, in which anannular space between the inner diameter of the smaller end of thestepped casting and the outer diameter of the bearing housing is fedwith oil through an extension of an oilway of the bearing housing, andthe reservoir receives oil from the annular space.
 3. A regenerative gasturbine engine according to claim 2, in which the oilway extension isfitted with a spring-loaded non-return valve which causes oil to beretained in the reservoir on shut down.
 4. A regenerative gas turbineengine according to claim 1 wherein an auxiliary gearbox suspendedbeneath one end of the bearing housing receives oil through drillingsand an oilway in the lower part of the bearing housing.